<?php
/**
 * Smarty plugin
 *
 * @package Smarty
 * @subpackage Security
 * @author Uwe Tews
 */

/*
 * FIXME: Smarty_Security API - getter and setter instead of public properties
 * would allow cultivating an internal cache properly - current implementation
 * of isTrustedResourceDir() assumes that Smarty::$template_dir and
 * Smarty::$config_dir are immutable the cache is killed every time either of
 * the variables change. That means that two distinct Smarty objects with
 * differing $template_dir or $config_dir should NOT share the same
 * Smarty_Security instance, as this would lead to (severe) performance penalty!
 * how should this be handled?
 */

/**
 * This class does contain the security settings
 */
class Smarty_Security {
	
	/**
     * This determines how Smarty handles "<?php/**
	 * This determines how Smarty handles "<?php .
	 * .. ?>" tags in templates.
	 * possible values:
	 * <ul>
	 * <li>Smarty::PHP_PASSTHRU -> echo PHP tags as they are</li>
	 * <li>Smarty::PHP_QUOTE -> escape tags as entities</li>
	 * <li>Smarty::PHP_REMOVE -> remove php tags</li>
	 * <li>Smarty::PHP_ALLOW -> execute php tags</li>
	 * </ul>
	 *
	 * @var integer
	 */

	public $php_handling = Smarty::PHP_PASSTHRU;
	/**
	 * This is the list of template directories that are considered secure.
	 * $template_dir is in this list implicitly.
	 *
	 * @var array
	 */
	public $secure_dir = array ();
	/**
	 * This is an array of directories where trusted php scripts reside.
	 * {@link $security} is disabled during their inclusion/execution.
	 *
	 * @var array
	 */
	public $trusted_dir = array ();
	/**
	 * List of regular expressions (PCRE) that include trusted URIs
	 *
	 * @var array
	 */
	public $trusted_uri = array ();
	/**
	 * This is an array of trusted static classes.
	 *
	 * If empty access to all static classes is allowed.
	 * If set to 'none' none is allowed.
	 * 
	 * @var array
	 */
	public $static_classes = array ();
	/**
	 * This is an array of trusted PHP functions.
	 *
	 * If empty all functions are allowed.
	 * To disable all PHP functions set $php_functions = null.
	 * 
	 * @var array
	 */
	public $php_functions = array ('isset', 'empty', 'count', 'sizeof', 'in_array', 'is_array', 'time', 'nl2br' );
	/**
	 * This is an array of trusted PHP modifers.
	 *
	 * If empty all modifiers are allowed.
	 * To disable all modifier set $modifiers = null.
	 * 
	 * @var array
	 */
	public $php_modifiers = array ('escape', 'count' );
	/**
	 * This is an array of allowed tags.
	 *
	 * If empty no restriction by allowed_tags.
	 * 
	 * @var array
	 */
	public $allowed_tags = array ();
	/**
	 * This is an array of disabled tags.
	 *
	 * If empty no restriction by disabled_tags.
	 * 
	 * @var array
	 */
	public $disabled_tags = array ();
	/**
	 * This is an array of allowed modifier plugins.
	 *
	 * If empty no restriction by allowed_modifiers.
	 * 
	 * @var array
	 */
	public $allowed_modifiers = array ();
	/**
	 * This is an array of disabled modifier plugins.
	 *
	 * If empty no restriction by disabled_modifiers.
	 * 
	 * @var array
	 */
	public $disabled_modifiers = array ();
	/**
	 * This is an array of trusted streams.
	 *
	 * If empty all streams are allowed.
	 * To disable all streams set $streams = null.
	 * 
	 * @var array
	 */
	public $streams = array ('file' );
	/**
	 * + flag if constants can be accessed from template
	 * 
	 * @var boolean
	 */
	public $allow_constants = true;
	/**
	 * + flag if super globals can be accessed from template
	 * 
	 * @var boolean
	 */
	public $allow_super_globals = true;
	
	/**
	 * Cache for $resource_dir lookups
	 * 
	 * @var array
	 */
	protected $_resource_dir = null;
	/**
	 * Cache for $template_dir lookups
	 * 
	 * @var array
	 */
	protected $_template_dir = null;
	/**
	 * Cache for $config_dir lookups
	 * 
	 * @var array
	 */
	protected $_config_dir = null;
	/**
	 * Cache for $secure_dir lookups
	 * 
	 * @var array
	 */
	protected $_secure_dir = null;
	/**
	 * Cache for $php_resource_dir lookups
	 * 
	 * @var array
	 */
	protected $_php_resource_dir = null;
	/**
	 * Cache for $trusted_dir lookups
	 * 
	 * @var array
	 */
	protected $_trusted_dir = null;
	
	/**
	 *
	 * @param $smarty Smarty       	
	 */
	public function __construct($smarty) {
		$this->smarty = $smarty;
	}
	
	/**
	 * Check if PHP function is trusted.
	 *
	 * @param $function_name string       	
	 * @param $compiler object
	 *       	 compiler object
	 * @return boolean true if function is trusted
	 * @throws SmartyCompilerException if php function is not trusted
	 */
	public function isTrustedPhpFunction($function_name, $compiler) {
		if (isset ( $this->php_functions ) && (empty ( $this->php_functions ) || in_array ( $function_name, $this->php_functions ))) {
			return true;
		}
		
		$compiler->trigger_template_error ( "PHP function '{$function_name}' not allowed by security setting" );
		return false; // should not, but who knows what happens to the compiler in
		              // the future?
	}
	
	/**
	 * Check if static class is trusted.
	 *
	 * @param $class_name string       	
	 * @param $compiler object
	 *       	 compiler object
	 * @return boolean true if class is trusted
	 * @throws SmartyCompilerException if static class is not trusted
	 */
	public function isTrustedStaticClass($class_name, $compiler) {
		if (isset ( $this->static_classes ) && (empty ( $this->static_classes ) || in_array ( $class_name, $this->static_classes ))) {
			return true;
		}
		
		$compiler->trigger_template_error ( "access to static class '{$class_name}' not allowed by security setting" );
		return false; // should not, but who knows what happens to the compiler in
		              // the future?
	}
	
	/**
	 * Check if PHP modifier is trusted.
	 *
	 * @param $modifier_name string       	
	 * @param $compiler object
	 *       	 compiler object
	 * @return boolean true if modifier is trusted
	 * @throws SmartyCompilerException if modifier is not trusted
	 */
	public function isTrustedPhpModifier($modifier_name, $compiler) {
		if (isset ( $this->php_modifiers ) && (empty ( $this->php_modifiers ) || in_array ( $modifier_name, $this->php_modifiers ))) {
			return true;
		}
		
		$compiler->trigger_template_error ( "modifier '{$modifier_name}' not allowed by security setting" );
		return false; // should not, but who knows what happens to the compiler in
		              // the future?
	}
	
	/**
	 * Check if tag is trusted.
	 *
	 * @param $tag_name string       	
	 * @param $compiler object
	 *       	 compiler object
	 * @return boolean true if tag is trusted
	 * @throws SmartyCompilerException if modifier is not trusted
	 */
	public function isTrustedTag($tag_name, $compiler) {
		// check for internal always required tags
		if (in_array ( $tag_name, array ('assign', 'call', 'private_filter', 'private_block_plugin', 'private_function_plugin', 'private_object_block_function', 'private_object_function', 'private_registered_function', 'private_registered_block', 'private_special_variable', 'private_print_expression', 'private_modifier' ) )) {
			return true;
		}
		// check security settings
		if (empty ( $this->allowed_tags )) {
			if (empty ( $this->disabled_tags ) || ! in_array ( $tag_name, $this->disabled_tags )) {
				return true;
			} else {
				$compiler->trigger_template_error ( "tag '{$tag_name}' disabled by security setting", $compiler->lex->taglineno );
			}
		} else if (in_array ( $tag_name, $this->allowed_tags ) && ! in_array ( $tag_name, $this->disabled_tags )) {
			return true;
		} else {
			$compiler->trigger_template_error ( "tag '{$tag_name}' not allowed by security setting", $compiler->lex->taglineno );
		}
		return false; // should not, but who knows what happens to the compiler in
		              // the future?
	}
	
	/**
	 * Check if modifier plugin is trusted.
	 *
	 * @param $modifier_name string       	
	 * @param $compiler object
	 *       	 compiler object
	 * @return boolean true if tag is trusted
	 * @throws SmartyCompilerException if modifier is not trusted
	 */
	public function isTrustedModifier($modifier_name, $compiler) {
		// check for internal always allowed modifier
		if (in_array ( $modifier_name, array ('default' ) )) {
			return true;
		}
		// check security settings
		if (empty ( $this->allowed_modifiers )) {
			if (empty ( $this->disabled_modifiers ) || ! in_array ( $modifier_name, $this->disabled_modifiers )) {
				return true;
			} else {
				$compiler->trigger_template_error ( "modifier '{$modifier_name}' disabled by security setting", $compiler->lex->taglineno );
			}
		} else if (in_array ( $modifier_name, $this->allowed_modifiers ) && ! in_array ( $modifier_name, $this->disabled_modifiers )) {
			return true;
		} else {
			$compiler->trigger_template_error ( "modifier '{$modifier_name}' not allowed by security setting", $compiler->lex->taglineno );
		}
		return false; // should not, but who knows what happens to the compiler in
		              // the future?
	}
	
	/**
	 * Check if stream is trusted.
	 *
	 * @param $stream_name string       	
	 * @return boolean true if stream is trusted
	 * @throws SmartyException if stream is not trusted
	 */
	public function isTrustedStream($stream_name) {
		if (isset ( $this->streams ) && (empty ( $this->streams ) || in_array ( $stream_name, $this->streams ))) {
			return true;
		}
		
		throw new SmartyException ( "stream '{$stream_name}' not allowed by security setting" );
	}
	
	/**
	 * Check if directory of file resource is trusted.
	 *
	 * @param $filepath string       	
	 * @return boolean true if directory is trusted
	 * @throws SmartyException if directory is not trusted
	 */
	public function isTrustedResourceDir($filepath) {
		$_template = false;
		$_config = false;
		$_secure = false;
		
		$_template_dir = $this->smarty->getTemplateDir ();
		$_config_dir = $this->smarty->getConfigDir ();
		
		// check if index is outdated
		if ((! $this->_template_dir || $this->_template_dir !== $_template_dir) || (! $this->_config_dir || $this->_config_dir !== $_config_dir) || (! empty ( $this->secure_dir ) && (! $this->_secure_dir || $this->_secure_dir !== $this->secure_dir))) {
			$this->_resource_dir = array ();
			$_template = true;
			$_config = true;
			$_secure = ! empty ( $this->secure_dir );
		}
		
		// rebuild template dir index
		if ($_template) {
			$this->_template_dir = $_template_dir;
			foreach ( $_template_dir as $directory ) {
				$directory = realpath ( $directory );
				$this->_resource_dir [$directory] = true;
			}
		}
		
		// rebuild config dir index
		if ($_config) {
			$this->_config_dir = $_config_dir;
			foreach ( $_config_dir as $directory ) {
				$directory = realpath ( $directory );
				$this->_resource_dir [$directory] = true;
			}
		}
		
		// rebuild secure dir index
		if ($_secure) {
			$this->_secure_dir = $this->secure_dir;
			foreach ( ( array ) $this->secure_dir as $directory ) {
				$directory = realpath ( $directory );
				$this->_resource_dir [$directory] = true;
			}
		}
		
		$_filepath = realpath ( $filepath );
		$directory = dirname ( $_filepath );
		$_directory = array ();
		while ( true ) {
			// remember the directory to add it to _resource_dir in case we're
			// successful
			$_directory [] = $directory;
			// test if the directory is trusted
			if (isset ( $this->_resource_dir [$directory] )) {
				// merge sub directories of current $directory into
				// _resource_dir to speed up subsequent lookups
				$this->_resource_dir = array_merge ( $this->_resource_dir, $_directory );
				return true;
			}
			// abort if we've reached root
			if (($pos = strrpos ( $directory, DS )) === false || ! isset ( $directory [1] )) {
				break;
			}
			// bubble up one level
			$directory = substr ( $directory, 0, $pos );
		}
		
		// give up
		throw new SmartyException ( "directory '{$_filepath}' not allowed by security setting" );
	}
	
	/**
	 * Check if URI (e.g.
	 * {fetch} or {html_image}) is trusted
	 *
	 * To simplify things, isTrustedUri() resolves all input to
	 * "{$PROTOCOL}://{$HOSTNAME}".
	 * So
	 * "http://username:password@hello.world.example.org:8080/some-path?some=query-string"
	 * is reduced to "http://hello.world.example.org" prior to applying the
	 * patters from {@link $trusted_uri}.
	 * 
	 * @param $uri string       	
	 * @return boolean true if URI is trusted
	 * @throws SmartyException if URI is not trusted
	 * @uses $trusted_uri for list of patterns to match against $uri
	 */
	public function isTrustedUri($uri) {
		$_uri = parse_url ( $uri );
		if (! empty ( $_uri ['scheme'] ) && ! empty ( $_uri ['host'] )) {
			$_uri = $_uri ['scheme'] . '://' . $_uri ['host'];
			foreach ( $this->trusted_uri as $pattern ) {
				if (preg_match ( $pattern, $_uri )) {
					return true;
				}
			}
		}
		
		throw new SmartyException ( "URI '{$uri}' not allowed by security setting" );
	}
	
	/**
	 * Check if directory of file resource is trusted.
	 *
	 * @param $filepath string       	
	 * @return boolean true if directory is trusted
	 * @throws SmartyException if PHP directory is not trusted
	 */
	public function isTrustedPHPDir($filepath) {
		if (empty ( $this->trusted_dir )) {
			throw new SmartyException ( "directory '{$filepath}' not allowed by security setting (no trusted_dir specified)" );
		}
		
		// check if index is outdated
		if (! $this->_trusted_dir || $this->_trusted_dir !== $this->trusted_dir) {
			$this->_php_resource_dir = array ();
			
			$this->_trusted_dir = $this->trusted_dir;
			foreach ( ( array ) $this->trusted_dir as $directory ) {
				$directory = realpath ( $directory );
				$this->_php_resource_dir [$directory] = true;
			}
		}
		
		$_filepath = realpath ( $filepath );
		$directory = dirname ( $_filepath );
		$_directory = array ();
		while ( true ) {
			// remember the directory to add it to _resource_dir in case we're
			// successful
			$_directory [] = $directory;
			// test if the directory is trusted
			if (isset ( $this->_php_resource_dir [$directory] )) {
				// merge sub directories of current $directory into
				// _resource_dir to speed up subsequent lookups
				$this->_php_resource_dir = array_merge ( $this->_php_resource_dir, $_directory );
				return true;
			}
			// abort if we've reached root
			if (($pos = strrpos ( $directory, DS )) === false || ! isset ( $directory [2] )) {
				break;
			}
			// bubble up one level
			$directory = substr ( $directory, 0, $pos );
		}
		
		throw new SmartyException ( "directory '{$_filepath}' not allowed by security setting" );
	}

}

?>